Method of treating corrosive gaseous fumes or smoke.



. ofTre-ating. Corrosive Gaseous Fumes jor.

- Sn1oke';-.and I do hereby declare the follow- UNITED STATES PATENToFFIoE.

CLARENCE B. SPRA'GUE, OF SALT s LTINe, REFINING &

LAKE CITY, UTAH, ASSIGNOR TO UNITED STATE MINING COMPANY, A CORPORATIONOF MAINE.

METHOD onranarmeoonnoslvn Gaseous FUMES R 'sMoKE.

To all a concemu' p Be it knownthat I, CLARENCE B. SPBAGUE,

a citizen ofothe United States, residing at ,-Salt. Lake City, in thecounty of Salt Lakehave invented. certain and State 'of Utah, new anduseful Improvements" in-Methods ing to be. a full, clear, of the.invention, skilled 'inY-the art exact desqription {snake andluse thesamefi ff corros ve 'gaseous fumes or smoke such as- -are produced inthe IOaStIIIg'DI othertreat The invention relates to the treatment of iiv.Jnoving from the smokevaluable metals and ..1netallic compoundsorcompounds andsubsin-noes which mi ht he injurious to vegetable'audannual lite if allowed -.to escape, into the atmo.sphere;

, #It iswell known tlu-itvthe gaseous fumes or tain' large quantities ofsulfur dioxidwhich emsts 1n the smoke 1n a gaseous state. 1 It is notthe purpose of thepresent invention to remove this. gas from the smoke.-The smoke producedin the, treat-mentgof inanyY-sulfid ores, eitherloecausefl of ,the composition of the ore or because; of the characterofthe treatment to which the. ores are subjected,-

also contains more or less sulfuric acid and other corrosive compoundswhich exist 1n the gaseous roducts as aivapor Oran a finely sion. Theseminute particles of condensed.

sulfuric acid and other solublecorrosive, compoundscollect upon theminute particlesof solidanatter known as fume, which are always presentin the smoke, and are deposited with the fume upon;the surrounding Vvegetation when :the smoke is dicharged into ,t-hesatmosphere, and havean 1n ur1ous cor-v .rosive action upon suchvegetation. The solidi-tune,in tIddlt-IOII to valuable-me'tals and metallic compounds,{alsofrequently contains poisonous compounds of arsenic and other substanceswhich notonly are injurious'to vegetation-but also render "anyvegetation upon which they may collect unfit for;

food or fodder.

lt'is the object'of, the

such as 'will enable others .t'oiwhich it appertains to I *fthroughcotton-or woolen filtering fabric.

solid state held in suspen- Specification 01 Letters Patent. p .TatentedAug. 17, 1909. Appllhation'aflledjlanuary 27, 19419. Serial-1Y0.474,392. I I

from the smoke produced in the roasting or other treatment ;of suchsulfid ores so "that the smoke maygbedischarged intoth'e atmospherewithoutfin jury to the surrounding vegetation, and any values containedin the fumema'y be reclaimed if desired. In cases Where the gaseousfumes or smoke predlicedin the treatment of ores are free from sulfuricacid and other corrosive comlpou'ndsy-it has been the'practice. to-some'ex- :tentto remove the. fume by filtration bags for the-purposeofrecove'ring the values contained in the fume. It has heretofore beenconsidered impracti'cable,':-however, to successfully filter the smoke[producedinthe treatment of man of the sulfid ores 'smok esproduced inthe roasting and smelting of the sulfid' ores of lead and copper,tecause-of the inevitable presence in the sn'ioke ofsulfuric"lat-idjaml'other corrosive (.Oll'iand especially thev poundswhich would quickly destroy the i have discovered that the minuteparticles =0f sulfuric acid or vother- "corrosive C0311- pounds held insuspensionin thewsmokc from ore roasting and otherfurnaces may besuccessfully neutralized so as to enable-the filtration of the smokethrough the fabric" by minglingu itlrthe smokei a pulverulentf attestedby the sulfur dioxidan'd-which is neutralizing agent which is,practically un held in suspension inthe'smoke 'for a suffi '0 ion tlength of time to hnitewith the corrosive compounds therein. The smokethus neutralized may :then -;be passed throughcloth bagswvithoutinjuryto the ba'gs,"and

thus the solid fume be completely-removed I therefrom. The invention-inits broader aspects contemplatesmingling the -pulveruy lent neutralizingagent, with the smoke in any suitable manner. v p Y I have also'foundthat a substantially complete neuti-alizationiof the smoke may besuccessfull 'veruleut neu .i'alizing agent into-the smoke fabric, and.-

further feature of theiii-vention,- p Y The neutrahzmgf agent maybejmingled with the smoke ata-ny desired point, andthe smoke, -'after itis .eooledto a temperature present invention to: removethe corrosiveconstituents and fume which .wil'lnot injurious-1y affect the fabric onits way; from the furnacekto the filtering 131118 manner of m ngling theneutralizing agent with the smoke forms a effected by introduclug'a.pul- '-1o0 through which it is ,to be filtered, is passed .relation toform non-corrosive compounds.

The acidity of any acid salts held in suspension in the fumes or gaswill also be neutral ized by the neutralizing agent, and any solublesalts or heavy metals, such as iron or copper, whichhave become moist oradhesive, and which wouldhave a destructive or corrosive action, Wlll bedecomposed by the neutralizing agent, and non-corrosive and.

unobjectionable compounds formed. The smoke as it comes 'to thefiltering fabric wlll therefore contain no corrosive compounds, and maybe filtered through the fabric without injury thereto. By thistreatment, there fore, metals, -metallic compounds, and poisonous and 1nurious compounds contained within the fume, and the corrosive and in-JllI'lOIlS compounds held in suspension,-are removedfrom the smokebefore it is Cl1S' charged into the atmosphere. The-danger of injury tovegetation is thus eliminated or reduced to a minimum, and the solidfume is collected so that any values contained therein may bereclaimedif desired by the proper subsequent treatment.

The invention in its broader aspectscontemplates the use of anysuitableneutralizing agent which in a pulverulent form has the propertyof neutralizing acids and the' acidity of acid salts, or of decomposingthe soluble salts-of heavy metals such as iron and co per when insolution. Oxid of zinc, oxid of magnesia, oxid orhydroxid of calcium,oXid or hydroxid of barium, thecarbonate and bicarbonate of .said bases,or the oxids, hydroxids, carbonates or bicarbonates of sodium andpotassium have this property to a greater or less degree, and areadapted for use as the neutralizing agent. I have found, however, thatzinc oxid is especially effective in securing a complete neutralizationof the corrosive compounds in the smoke when mingled with the smoke in a.pulverulent form, and the use of this oxid, either alone or inconnection with other neutraliz- -ing compounds as the neutralizingagent constitutes a further feature of the invention.

In cases where the' quantities of sulfuricacid and other corrosive comounds in the smoke are comparatively sma l, I prefer to use pulverulentzinc oxid alone to neutralize the smoke, since a comparatively smallquantity of this oxid when mingled with the smoke will effectively andcompletely neutralizethe sulfuric acid and other corrosive compounds. Incases where the per cent. of sulfuric acid and corrosive compounds iscomparatively, large, I have found that an effective and-completeneutralization of. the smoke may be secured by introducing into thesmoke finely divided slaked lime and at the same time or thereafterintroducing a small amount of zinc oxid. The slaked lime unites with thegreater portionof the sulfuric acid and other corrosive compoundscontained within the smoke, and the zinc -oxid completes theneutralization by uniting with whatever corrosive compounds would remainin the smoke but for its introduction.

In practicing the invention, the, neutralizing agent may be introducedinto the smoke on its way from the furnace to the filtering fabric atany. desired-point, and'in any-suitable manner. For instance, it may besuccessfully introduced I into a flue through which the smoke passes byblowing it into the flue, or by an ordinary roller feed, the velocity ofthe gases being such in either case. that the neutralizing agent is heldin suspension in the smoke a suliicient length of time to unite with thecorrosive compounds therein. The neutralizing agent may also besuccessfully introduced into the smoke by feeding-it into the inlet ofthe fan which blows the gases into the bag-house where thesmoke isfiltered. In the latter case, the solid particles of the neutralizingagent are held in suspension a suflicient length of time to efiect thethorough neutralization of the corrosive compounds before the smokecomes in contact with the filter bags.

- In using zinc oxid as the neutralizing agent, it may be advantageouslyintermingled with the smoke by providing a spe cial furnace in whichsuitable uantities of zinc ore are roasted, and disc iarging the zincoxid produced in this furnace into the flue through which the. smoke'tobe treated passes. The zinc oxid fume produced inthe furnace, anddischarged into the fiue,.is in a state of fine subdivision, and isthoroughly intermingled with the gases and their accompanying fume. .Theoxid, therefore, is

brought into intimate relation'with the fine particles of sulfuric acidor other corrosive compound held in suspension in the gases, or

which may have collected on the particles of to form non-corrosivecompounds. Thesulfur dioXid in the gases ispractically without efiect onthe zinc oXid, and the zinc oXid therefore need be present only insufficient quantities to neutralize the sulfuric acid and corrosivecompounds.

thoroughly mixed with the gases, and arefume, and combines withthesecompounds The form of apparatus utilized in practicing theinvention is not material, and it may be ofany well known or usualconstructi'on.

\ Having set forth the nature andobject of the invention, what Iclaim-is:- .3 j Y 1. The method of treatingcorrosive gaseous fumes orsmoke from ore treating furnaces for the purpose of removing injuriousor valuable compounds therefrom consisting in introducing into from thefurnace a pulverulent neutralizing j agent which is held in suspensionin the' the smoke on-its way smoke and unites with the, corrosive compounds therein to form non-corrosive compounds, substantially asdescribed.

2. The method of treating corrosive'gase ous fumes ,or naces for thepurpose of removing injurious or valuable compounds therefrom,consisting in introducing into the smoke on its way from the furnace apulverulent neutralizing agent which is held in suspension in the smokeand unites with the corrosive compounds therein to form non-corrosivecom' pounds, and thereafter filtering the smoke to remove the fume,substantially'as describeda 3. The method of treating corrosive gaseousfumes or smoke fromore treating-fur naces for the purpose of removinginjurious or valuable compounds therefrom, consisting in introducinginto the 7 from the furnace a pulverulent neutralizin agent comprisingzmc oxid, which is held in suspension in the 'smoke and unites with thecorrosive compounds to forlnnon-cor rosive, compounds, and thereafterfiltering the smoke to remove the fume,substantially as described. I

4. The method of neutralizing the cor rosive constituents of corrosivegaseous fumes or smoke consisting in mingling therewith a pulverulentneutralizing agent which is.

held in suspension therein and unites with the corrosive compounds toform non-corrosive compounds, substantially as described.

smoke from ore treating fursmoke on .its way- 5. The method of treatingcorrosive gaseous fumes or smoke for the purpose of removlng in urious.or

smoke a pulverulent neutralizlng'agent, such as pulverulent lime, whichunites with the major portion of the corrosive compounds, completing theneutralization by mingling pulverulent, zinc oxid "with the smoke, and

tering fabric to remove tially as described.

7 The method of treating corrosive gasefumes or smoke for the purpose ofrethe fume, substanous moving injurious or valuable compoun'dstherefrom, consistlng 1n mingling therewlth "a pulverulent neutralizingagent which unites with the corrosive compounds in the smoke to formnon-corrosive compounds, and thereafter filtering the fume,substantially as described.

8. Themethod oftreatingcorrosive gaseousfumes or smoke for the purposeof removing injurious 'or valuable compounds therefrom,

a pulverulent neutralizing agent comprising which unites with thecorrosive compounds in the "smoke to form non-corconsisting in minglingtherewith rosive compounds, and thereafter filtering the smoke toremove, the fume, substantially as described. I

-- In testimony whereof I aflix my signature,

in. presence of two' witnesses.

' CLARENCE B. SPRAGUE.

Witnesses:

' ANDREW Ho'wA'r,

R. 'H. BU'rrnRFmLn.

valuable compounds-- therefrom consisting in mingling with the.

thereafter passing the smoke through a filsmoke to remove the a

